Nice work Suzy!
Don't know if you're aware but you have to be careful doing visual observations of red stars like Mira. AAVSO recommend the 'quick glance' method, not letting your gaze linger on the red star. If you stare for an extended time at red stars they may appear to be unduly bright compared to blue stars, because red stars tend to excite the retina (Purkinje effect). This can lead to errors in relative magnitude. There are other methods involving de-focusing etc, some of which remain a little 'controversial'.
http://www.aavso.org/sites/default/f...nglish_ch3.pdf
Good luck with it!
Cheers -